A mobile computing device may provide voice and data communications functionality, as well as computing and processing capabilities. For voice and data communications, a mobile computing device typically employs one or more radio transceivers and one or more antennas. Antenna design for a mobile computing device is an important consideration and is often limited by strict performance constraints.
In some cases, a mobile computing device may support multiple modes of communication using the same band of the radio frequency (RF) spectrum. For example, the mobile computing device may enable Bluetooth communication over a personal area network (PAN) as well as Wireless Fidelity (WiFi) communication over an Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless network using the 2.4 GHz range of the industrial, scientific and medical (ISM) frequency band. Although Bluetooth and 802.11 radio transceivers each utilize spread spectrum modulation techniques, if located on the same platform, strong surface current may lead to significant mutual coupling and coexistence interference when two antennas are working simultaneously.
For a mobile computing device with a small form factor (e.g., ID of 110 mm×60 mm or smaller), coexistence interference is especially problematic. Accordingly, there exists the need for improved antenna designs for reducing frequency coexistence interference.